Add test for 32724 (#36789)

Author: phofl

pandas/tests/window/test_rolling.py

@@ -824,3 +824,14 @@ def test_rolling_axis_1_non_numeric_dtypes(value):
     result = df.rolling(window=2, min_periods=1, axis=1).sum()
     expected = pd.DataFrame({"a": [1.0, 2.0]})
     tm.assert_frame_equal(result, expected)
+
+
+def test_rolling_on_df_transposed():
+    # GH: 32724
+    df = pd.DataFrame({"A": [1, None], "B": [4, 5], "C": [7, 8]})
+    expected = pd.DataFrame({"A": [1.0, np.nan], "B": [5.0, 5.0], "C": [11.0, 13.0]})
+    result = df.rolling(min_periods=1, window=2, axis=1).sum()
+    tm.assert_frame_equal(result, expected)
+
+    result = df.T.rolling(min_periods=1, window=2).sum().T
+    tm.assert_frame_equal(result, expected)